Welcome back Traver. Seems like a couple of Lifetimes ago when we were talking about CE2's. LOL.
Your questions are Hard to Answer. Because about All we have to go on is Old Drafts and a Single New Draft FDA Document.
But here is my Opinion.
Only liquids with nicotine? Yes and No with a chance of Maybe. Pure PG, Pure VG and Flavorings are not going to be Regulated any more then as they are Today. If you combine them All Together and Market/Advertise them as an "e-Liquid", then Yes, I think they will. If you mix them Together and don't Market/Advertise them as an "e-Liquid" or to be consumed, then No, I don't think they will. But this is where the Maybe could be applied.
Would it apply to artificial nicotine? No. If Nicotine is Not Derived from Tobacco Plants than I do Not Believe that the FDA has the Authority to Regulate Artificial Nicotine for Recreational Use.
Devices that vaporize nicotine? If the Device is Marketed/Advertise as such, or have previously been Marketed/Advertised to, or is Sold with a Product that contains Nicotine derived from Tobacco Plants, then Yes, I believe it will fall under FDA Authority.
Devices that vaporize any liquid? Any Liquid, Maybe? A Lot depends on how it is Marketed/Advertised. And this is going to be an Area where I think you are going to see Legal Challenges.
Like I said, this is All just an Opinion. And I'm sure there will be Some who Agree or Disagree with Some or All of This.